Yarn tension releasing attachment for sewing machines



March 17, 1970 G. PESCHKE 3,5

YARN TENSION RELEASING ATTACHMENT FOR SEWING MACHINES Filed June 7, 1968 In van/or.- 6M1! 16 PE? (E United States Patent Ofice Patented Mar. 17, 1970 Int. (:1. wish 47/00 U.S. Cl. 112-254 4 Claims ABSTRACT OF THE DISCLOSURE A device for releasing yarn tension in sewing machines during use thereof consisting of a gripping disc tensioning means adapted to be quickly fitted to various types of machines, by inexperienced personnel, and which ensures satisfactory operation thereof.

The invention relates to an attachment for releasing yarn tension in sewing machines, which has a gripping disc tension device. The main object of the invention is to provide an attachment for releasing the yarn tension, which can be fitted later and quickly to sewing machines and, if necessary, by inexperienced people, and which ensures satisfactory operation.

Yarn tension releasing devices for later attachment which are known to date all have the drawback of the gripping discs lifting on one side, which may cause the yarn of the raised gripping discs to become trapped. This invention lies in the provision of an attachment for releasing the yarn tension in sewing machines which has a gripping disc tension device, and in that the attachment for releasing the yarn tension comprises a motive source, for example an electric plunger type armature magnet, which can be fitted subsequently to the sewing machine, and a connection 'between the armature of the plunger type armature magnet and the outer gripping disc. Advantageously the design is such that the connection between magnet armature and outer gripping disc is designed as a double lever with a fulcrum support resting on the sewing machine and forming a support for the double lever. Furthermore it is advisable to design the outer gripping disc and the double lever as one piece, preferably with the free end as an eye.

In order to equip a sewing machine with the yarn tension releasing device according to the invention it sufiices to replace the gripping disc of the existing yarn tension device by the eye of the double lever and to fit the plunger type armature magnet to the sewing machine for example by means of a bracket. Thus, the yarn tension releasing device is operable and, upon actuation of the plunger type armature magnet or solenoid, the outer gripping disc which is now formed by the eye of the lever, is elfectively raised on all sides. Furthermore the double lever returns unhindered into its initial position when the magnet is deenergised and the eye of the lever again carries out its function as a yarn tensioner.

In order to make it possible for the motive source to be kept relatively small it is advisable to construct the fulcrumed lever arm nearer the magnet considerably longer than the arm near the gripping disc. Furthermore it is advisable to design the bearing support of the lever as a screw whose height is adjustable. Thus the device can be simply adjusted when being attached.

When using the yarn tension releasing device according to the invention it is possible to omit the thrust washer which may be provided in the gripping disc tension device.

The invention is hereinafter explained with reference to the drawing, illustrating an example in which are:

FIGURE 1 is the usual gripping disc tension device,

FIGURE 2 is the yarn tension releasing device according to the invention in side view,

FIGURE 3 is the device according to FIGURE 2 in plan view.

The usual gripping disc tension device consists of the tension rod 1, the inner gripping disc 2, the outer gripping disc 3, the thrust washer 4, the volute spring 5 and the tension regulator nut 6. The upper yarn 7 runs between the gripping discs 2 and 6.

In the inventive device for releasing the yarn tension according to FIGURES 2 and 3, the outer gripping disc 3 is rigidly connected to one end of the double lever 8. In the practical design it is formed by an eye 9 provided on the double lever 8. The double lever 8 and its eye 9 are made in one piece, for example from sheet metal. The arm 10 of the double lever 8, which is further from the gripping discs is rigidly connected to the armature 11 of the electric plunger type armature magnet 12. The latter may be fixed to the sewing machine 14 by means of the bracket 13. The double lever 8 is fulcrumed by means of a screw 15, which is adjustable in height and is lockable by means of a counter nut 16. The screw 15 only rests on the surface 18 of the sewing machine with its free end 17, i.e. it is not rigidly connected with the sewing machine.

The armature 11 ends in a threaded journal 19 by which the height of the double lever 8 can be adjusted by means of the nuts 20, 21.

The arm 10 near the magnet of the double lever is considerably longer than the arm 22 near the gripping disc. As an example the former measures 9 cm., whilst the arm 22 only measures 3 cm.

The thrust washer 4 may be omitted if desired. In this case the volute spring 5 is directly supported by the eye 9.

If the solenoid 12 is energized and the armature 11 is displaced in the direction of the arrow A, then the holder 9 is raised so that the pressure of the spring 5 has no effect, and the upper yarn 7 is not checked, which, for example, is desirable in the case of a sewing machine which is equipped with a yarn severing device when its blade is withdrawn.

As soon as the magnet 12 is de-energized the double lever 8 returns to its initial position in which the volute spring 5 presses the holder 9 against the inner gripping disc 2, so that the upper yarn 7 is checked again.

What I claim is:

1. A yarn tension releasing attachment in sewing machines having a gripping disc tension device comprising an inner gripping disc and an outer gripping disc includng biasing means for mutually biasing said discs toward each other, an electrical actuated solenoid having means operatively connected to the outer gripping disc including a fulcrumed lever having two arm portions, one arm being interconnected between said solenoid and one of said discs to displace said disc against the biasing means and away from said other disc when said solenoid is actuated.

2. A yarn tension releasing device according to claim 1, wherein one of said arm portions of said fulcrumed lever which is nearer to the solenoid is longer than the other arm of the fulcrumed lever nearer to the gripping discs.

3. A yarn tension releasing device according to claim 2, wherein a fulcrum point for said lever comprises a screw 3 4 support means-therefor wherein the height of the ful- 2,582,211 1/1952 Turner 112254 crurn point is adjustable. 2,925,058 2/ 1960 Conrad 112-254 2,938,479 5/1960 Armstead 112-254 4. A yarn tension releasing device according to claim 3,

wherein one of said gripping discs is formed integrally with said fulcrurned lever. FOREIGN PATENTS 5 688,101 2/1940 Germany.

References Cited MERVIN STEIN, Primary Examiner UNITED STATES PATENTS 281,650 7/1883 Thomas 112 241 1,443,460 1/1923 Crofford 112-255 10 GEORGE H. KRIZMANICH, Assistant Examiner 

